As compared with silicon semiconductor devices currently mainly used, a silicon carbide semiconductor device has many advantages such as small power loss and operability under a high temperature, and is expected as a next-generation power semiconductor device. Conventionally, various structures have been proposed for structures of semiconductor devices. For example, in a trench gate structure, a groove called “trench” is provided in a semiconductor substrate (for example, see Japanese Patent Laying-Open No. 2012-146921 (Patent Document 1)).